Evaporator restrictor



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INVENTOR. JAMES A.HALL

ATTORNEY United States Patent-O EVAPORATOR RESTRICTOR James A. Hall, Louisville, Ky., Metals Company, Louisville, Delaware assignor to Reynolds Ky., a corporation of The .present invention relates to heatexchangers, and relates .in particular to an evaporator compartment for a refrigerator.

In the application of Richard E. Gerhardt, Serial No. 470,959 filed November 24, 1954, for Refrigeration Compartment, Patent 2,776,549, issued January 18, 1957, a refrigeration compartment is shown which has a back in which is located a receiver and an accumulator, the receiver being of special design and embodying a restriction between the receiver and evaporator to assist in emptying the receiver during the defrosting cycle. The compartment is constructed by roll bonding two metal sheets with a resist pattern therebetween and then dilating the um bonded areas to form the receiver chamber and other passages and chambers. However, in this method of manufacture, it is not possible to accurately gauge the size of the restriction, so the size of the restriction in different units will vary, and this causes a variation in the operation of the apparatus during defrosting.

it is an object of the present invention to provide a refrigerator compartment incorporating a receiver, in which the orifice between the receiver and evaporator is maintained of controlled fixed size.

A further object is the provision of such a structure which permits the insertion into the apparatus of a ferrule having a controlled fixed size orifice.

The invention is described in detail in the following specification taken in connection with the accompanying drawing illustrating a preferred embodiment by way of example, and wherein:

Figure l is a rear elevation view of a compartment, with part broken away;

Figure 2 is a section taken on line II-II of Figure 1, and

Figure 3 is a view similar to Figure 2 of a modification.

Referring to the drawing, Figure l, the back wall 1 of the evaporator compartment has a chamber 2 which serves as a receiver for liquid refrigerant. This compartment preferably is constructed from a T-shaped plate or blank, formed by roll bonding together two sheets of metal in face to face relation with a weld resist pattern therebetween, and then dilating the unbonded areas protected by the resist pattern to form the various passageways and chambers. The plate then is bent into the compartment shape, substantially as disclosed in said Gerhardt application. This compartment has a bottom integral with the back wall, in which is located the passages forming an evaporator chamber, and has a top and side walls carrying suitable passages and chambers.

An inlet passageway 3 extends from the edge 4 of the back wall, and connects with a vertical passageway 5 leading to the evaporator inlet. This passageway 3 is located above the receiver chamber 2 and is spaced from this chamber by an integrally bonded portion 6 of the wall. The protuberant receiver chamber 2 connects at the top with passage 3 by a flow passage 7 and a second flow passage 8 connects the bottom of the receiver chamice 2. her with the inlet passage 3 in' advance of vertical passageway 5;

The accumulator chamber 9- is located on the back wall, and its discharge connection 10 extends to the edge 4. Itwill be'observed'the inlet passage 3 extends from the edge 4'of'the wall as a substantially straight duct of substantially uniform cross sectional area.

Within this passage 3'is' a bushing 11 positioned betweenthe flow passages 7 and 8. This bushing has a close,'substantiallysealing fit withthe walls of passage 3 and has an-orifice 1230f predetermined size therethrough.

This bushing'may' be inserted intopassage 3 from .the open end at edge 4 after the passages and chambers have been dilated, either before the-flat plate is bent into shape, or after the plate 'is. bent into the compartment shape. Preferably" it is forcediinto'the passage with a tight friction fit; This bushing may 'be made ofv any suitable metal, such as, for example; copper; brass or aluminum. Byprefabricating'the bushing with an accurately formed metering orifice, variations in size thereof are avoided.

In the modification shown in Figs. 1 and 2 the passage 3 is approximately half round incross section, and the bushing 11 accordingly is of similar shape. Such a shape of the passage is produced by dilating the sheet on one side only of the resist pattern.

In the modification shown in Fig. 3, the sheets on both sides of the resist pattern are dilated to produce a passage 3' that is round or oval in cross section. In such embodiment, the plug or bushing 11' is similarly shaped to fit into the passageway.

The operation of the specially designed receiver is explained as follows. During the refrigeration cycle, liquid refrigerant is admitted into the left end of passageway 3 as shown in Fig. 1 and by gravity discharges through flow passage 7 into the receiver chamber 2. Some evaporation of the liquid refrigerant will take place in the receiver 2 thereby cooling the surrounding walls of the receiver. When the receiver 2 is substantially filled with liquid, the liquid in the passage 8 overflows into the vertical passageway 5 joined to the evaporator coil. The other end of the evaporator coil is joined to the lower end of the accumulator chamber 9 which insures that all the liquid refrigerant is evaporated prior to entering the outlet passageway 10.

During the defrosting cycle, hot gas under a higher pressure is admitted into the left end of the passageway 3, and due .to the restrictive orifice 12 in bushing 11, forces the liquid refrigerant out of the receiver chamber 2, through the passageway 5 and into the evaporator proper. At the same time some of the gas escapes through the orifice 12 of the bushing 11 and mixes with the liquid refrigerant being discharged into the passageway 5.

The evaporator coils are defrosted as the hot gas traverses them. Due to the gas being under a higher pressure, there will be substantially no evaporation of the liquid refrigerant which will remain distributed throughout the evaporator coil after the defrosting cycle is finished. Once the pressure is again lowered in the evaporator, the distributed liquid refrigerant will immediately start evaporating to again initiate the refrigeration process.

As explained in the present application, the orifice 12 in bushing 11 should be of a particular size to produce the desired mixture of hot gases and liquid refrigerant and to properly distribute the liquid refrigerant throughout the evaporator coils during the defrosting cycle so as to cause the refrigeration cycle to begin immediately after the end of the defrosting cycle.

I claim as my invention:

1. A heat exchanger structure comprising: a vertical pressure welded passageway panel constructed of at least two superposed sheets pressure welded together in faceto-face relationship and having an expanded passagewayforming system of unwelded areas between them providing a chamber, an inlet passageway and a pair of flow connections; said chamber being located in said vertical panel and being adapted in operation to receive liquid refrigerant; said inlet passageway being located above the upper edge of said chamber; the first of said flow connect-ions being located adjacent one end of said chamber and interconnecting the top of said chamber and said inlet passageway; the second of said flow connections being located adjacent the opposite end of said chamber and interconnecting the bottom of said chamber and said inlet passageway; and a separate bushing having a flow orifice therethrough of predetermined size and being positioned to seal said inlet passageway between said flow connections except for said orifice.

2. The structure of claim 1 wherein: said inlet passageway extends along a straight line from an inlet opening in one edge of said sheets to the point at which said bushing is located.

3. In the art of making bonded-sheet passageway panels of the refrigerant evaporator type having a vertical wall section containing a receiver chamber having an upper inlet and a lower outlet, an improved method of manufacture comprising: providing said passageway panel with an inlet passageway extending along a straight line from an inlet opening in one edge of the panel to a predetermined point beyond a first branch connection with said upper inlet but short of a second branch connection with said lower outlet; providing, for the straight portion of said inlet passageway, a bushing having a metering orifice of predetermined size; and inserting said bushing through said edge inlet into said inlet passageway and positioning it at said predetermined point to seal said inlet passageway between said branch connections except for said orifice.

References Cited in the file of this patent UNITED STATES PATENTS 1,590,513 Hulse June 29, 1926 2,319,498 Gerard May 18, 1943 2,776,549 Gerhardt Jan. 8, 1957 2,821,845 Thomas Feb. 4, 1958 

